Washinton, D.C. - U.S. Ambassador to Mexico Roberta Jacobson announced via a Twitter post on March 1 that she will be leaving her position on May 5, 2018.

Politico reported that it had obtained a copy of a memo that Jacobson sent to her staff in which the ambassador wrote that her decision was "difficult" and acknowledged that it came at a "crucial moment" in U.S.-Mexican relations. However, Jacobson did not explain exactly why she decided to resign, nor did she address the administration's plans to replace her.

Multiple news sources, including the Mexican newspaper Reforma, which broke the story on March 1, reported that Edward Whitacre, Jr., the former CEO of General Motors and AT&T, is considered to be President Trump's nominee to replace Jacobson. The Washington Post also reported that official sources in both countries had confirmed Whitacre is the president's choice for the ambassadorship.

Politico cited a March 1 statement from Mexico's Foreign Ministry, which said Secretary of State Rex Tillerson told Mexican officials on February 17 that Jacobson was resigning and later submitted a name to the Mexican government for its approval.

This diplomatic convention is known as an agrément - a specialized term in the field of international affairs that refers to the agreement by a state to receive members of a diplomatic mission from a foreign country. The ministry said it granted agrément on February 26, but it declined to name the would-be nominee, saying that was the responsibility of the U.S. government.

"The Foreign Ministry appreciates Ambassador Jacobson's committed and responsible diplomacy as ambassador, not only in Mexico but also for the benefit of the entire region," the Mexican ministry said.

The Washington Post reported that State Department Undersecretary Steve Goldstein confirmed that Jacobson has announced her intention to retire and also that Jacobson told Secretary of State Rex Tillerson about her decision when he was in Mexico last month.

"We are grateful to her, and we are sorry to see her go," Goldstein said.

A report in The Hill observed that Whitacre has deep ties to Mexico, including a friendship with the country's richest man, Carlos Slim.